Yahoo! Science > Biology
The famous portals' comprehensive directory of biological science references, with tens of thousands of relevant links to be found.
http://dir.yahoo.com/Science/Biology/

Bioexplorer: Biology Links
Links to websites involved in the biosciences, split into over 20 sub-branches so that you can easily navigate to the science field you want to know more about.
http://www.bioexplorer.net/

Google Directory > Science > Biology
The popular search engines' DMOZ directory clone offering a collobarated and categorized directory of pages and websites in the biological sciences.
http://directory.google.com/Top/Science/Biology/

Spolem.co.uk Biology & Science Links
Categorized directory of the biological sciences and further afield, particularly emphasizing resources for those studying A-Level biology (16-18 year olds).
http://www.spolem.co.uk/alevel_home.htm

Biology Search Engines
A one page directory listing the numerous search engines available on the web, tailor made to find information in the biological sciences.
http://www.internets.com/sbiology.htm

Biolinks.com Biological Sciences Directory
Categorized directory and search facility courtesy of biolinks.com. Search through the various areas of the biological sciences to find out more about each respective area.
http://www.biozone.co.nz/links.html

The Virtual Library : Biosciences
Clearly designed, categorized listings of biology and biological science related websites all to be found online, courtesy of the virtual library catalogue.
http://vlib.org/Biosciences.html

Sites for teachers
Hundreds of educational websites ranked by popularity
http://www.sitesforteachers.com/index.html

GoPubMed - Search PubMed and get results sorted by GO and MeSH
It retrieves PubMed abstracts for your search query, detects
terms from the Gene Ontology (GO) and Medical Subject Headings (MeSH) in
the abstracts and allows you to browse the ontologies and display only
papers containing specific GO and MeSH terms
http://www.gopubmed.com